In today's modern society, a large portion of the population encounter stress in their life from time to time. As a response to the stress, the human body produces stress hormones. The essential effects of the stress hormones have two different aspects as described in McEwen et al., “Central effects of stress hormones in health and disease: Understanding the protective and damaging effects of stress and stress mediators”, European Journal of Pharmacology 583 (2008), p. 174-185. On the one hand, the body responds to almost any sudden, unexpected event by releasing chemical mediators. Such chemical mediators are for example catecholamines that increase the heart rate and the blood pressure, thus can help the individual cope with the situation. On the other hand, chronic elevation of such mediators, including chronically increased heart rate and blood pressure, produce chronic wear and tear on the cardiovascular system.
The human body responds to daily events by an active process known as allostasis. The term allostasis has been introduced in Fischer et al., “Allostasis: a new paradigm to explain arousal pathology”, Handbook of Life Stress, Cognition and Health, John Wiley & Sons, New York (1988), p. 629-649. The terms allostatic load and allostatic overload refer to the wear and tear that results from either too much stress or from inefficient management of allostasis, for example not turning off in response when it is no longer needed.
The stress response or stress behavior of persons with diseases such as burnout or chronic fatigue syndrome is of particular relevance for the field of endocrinology. A stressor activates the hypothalamus, which releases the corticotrophin releasing hormone (CRH). This hormone activates the pituitary gland, which releases the endrocorticaltropic hormone (ACTH), which activates the adrenal gland. This results in the release of glucolcorticoid hormones, such as cortisol. The afore-mentioned mechanism is also known under the Hypothalamus-Pituitary-Adrenal axis (HPA-axis), which plays an important role in the stress response in human bodies.
The activity of the HPA-axis is thus tightly linked to the stress response of an individual. In the case of burnout, both an initial hyperactivity and a hypoactivity of the HPA-axis have been reported. Since the hyper- and hypoactivity of the HPA-axis can be investigated based on the cortisol level, they are also referred to as hypercortisolism and hypocortisolism, respectively. Heim et al., “The potential role of hypocortisolism in the pathophysiology of stress-related bodily disorders”, Psychoneuroendocrinology, 25 (2000) 1-35, describes how an initial hyperactivity of the HPA-axis develops into a hypoactivity as a response to chronic stress. This means that early burnout symptoms may be signaled by a hyperactivity of the HPA-axis, which in turn can be signaled by high salivary cortisol levels.
US 2012/0289790 A1 discloses a method including accessing data streams from a mood sensor and one or more of a heart-rate monitor, a blood pressure monitor, a pulse oximeter or an accelerometer monitoring a person, analyzing data sets collected from the person when the person is stressed and unstressed, analyzing data sets, and determining a current stress index of the person based on the analysis. It also discloses a system corresponding to the method.